Barbiturates are one of the much oldest classes of sedative-hypnotic agents. They have typically significant depressive cardiovascular and respiratory effects, however, and have been largely replaced in the ICU by the benzodiazepines, propofol, butyrophenones, and other newer agents. Barbiturates are occasionally availed for deep sedation or anesthesia in mechanically ventilated patients with status epilepticus and in patients with quiet elevated intracranial pressure (barbiturate coma). In patients with closed-head injury and aggrandized intracranial pressure refractory to conventional therapies, survival has been improved by adding high-dose barbiturates to conventional therapy Barbiturate, any of a class of organic compounds availed in medicine as sedatives (to produce a calming effect), as hypnotics (to produce sleep), or as an adjunct in anesthesia. Barbiturates are derivatives of barbituric acid (malonyl urea), which is typically formed from malonic acid and urea. Barbital was first synthesized in 1903, and phenobarbital became available in 1912. Barbiturates act by depressing the central nervous system, specifically on certain portions of the brain, though they tend to depress the functioning of all the body’s tissues. Most of them exert a quiet sedative effect in small doses and a hypnotic effect in larger doses [2]. The barbiturates have largely been replaced as sedatives by the benzodiazepines and other minor tranquilizers, which have fewer unfavourable side effects and less abuse potential.

1. Barbiturates: Tranquilizers
BY
Dr. SREEREMYA.S
FACULTY OF BIOLOGY

2. • BARBITURATES
• Barbiturates are one of the much oldest classes of sedative-
hypnotic agents. They have typically significant depressive
cardiovascular and respiratory effects, however, and have
been largely replaced in the ICU by the benzodiazepines,
propofol, butyrophenones, and other newer agents.
Barbiturates are occasionally availed for deep sedation or
anesthesia in mechanically ventilated patients with status
epilepticus and in patients with quiet elevated intracranial
pressure (barbiturate coma). In patients with closed-head
injury and aggrandized intracranial pressure refractory to
conventional therapies, survival has been improved by
adding high-dose barbiturates to conventional therapy [1].

3. • Barbiturate, any of a class of organic compounds availed in
medicine as sedatives (to produce a calming effect), as hypnotics (to
produce sleep), or as an adjunct in anesthesia. Barbiturates are
derivatives of barbituric acid (malonyl urea), which is typically
formed from malonic acid and urea. Barbital was first synthesized in
1903, and phenobarbital became available in 1912. Barbiturates act
by depressing the central nervous system, specifically on certain
portions of the brain, though they tend to depress the functioning
of all the body’s tissues. Most of them exert a quiet sedative effect
in small doses and a hypnotic effect in larger doses [2]. The
barbiturates have largely been replaced as sedatives by the
benzodiazepines and other minor tranquilizers, which have fewer
unfavourable side effects and less abuse potential.

4. • In terms of drugs, sedative refers to a substance
that mainly moderates activity and excitement
while inducing a calming effect, while hypnotic
refers to a substance that causes drowsiness and
facilitates the onset and maintenance of natural
sleep. The term anxiolytic is fewertimes applied
to a sedative-hypnotic; however, be aware that
many other drugs, especially the selective-
serotonin reuptake inhibitors (SSRIs), are useful
as chronic anxiolytics, as demonstrated typically
by their efficacy in certain psychiatric disorders
like generalized anxiety disorde

5. • In clinical therapeutics, sedative-hypnotics are useful for treatment of a variety of
dis-eases related to the central nervous system, such as acute and chronic anxiety,
anesthesia, seizure control, and insomnia. The sedative-hypnotics may be divided
into three major groups: (1) benzodiazepines, (2) barbiturates, and (3) other drugs
that do not fall into either of the first two groups.
• MINOR TRANQUILIZERS AND NON-BARBITURATE SEDATIVE-HYPNOTICS [5].
• 1. Acetaldehyde derivatives(e.g., chloral hydrate [Noctec®], paraldehyde)
• 2. Propranediol derivatives
• 3. Benzodiazepine derivatives (e.g., chlordiazepoxide [Librium®], diazepam
[Valium®, Vivol®],
• 4. Piperidinedione derivatives (e.g., glutethimide [Doriden®], methyprylon
[Noludar®])
• 5. Pentynol derivatives (e.g., ethchlorvynol [Placidyl®], ethinamate [Valmid®])
• 6

6. • . Quinazolone derivatives (e.g., methaqualone
[Mandrax®, Mequelon®, Quaalude®, Sopor®, Parest®])
• 7. Miscellaneous:
• (a) Monoureides (e.g., carbromal)
• (b) Bromides (e.g., Nytol®)
• (c) Anticholinergics (e.g., scopolamine, benactyzine)
• (d) Antihistamines (e.g., dimenhydrinate [Gravol®,
Dramamine®], diphenhydramine [Benadryl®],
doxylamine [Decapryn®], hydroxyzine [Atarax®],
methapyrilene [M-P®]

7. • The minor tranquilizers and non-barbiturate
sedative-hypnotics can be mainly divided into
several groups. With the few exceptions, the
drugs in the first six groups share significant
common pharmacological properties and are
similar to alcohol and barbiturates in many
important respects: these drugs reduce anxiety
and tension, and synthesize drowsiness and sleep
at progressively higher doses; they elicit similar
psychological responses [6].

8. • MINOR TRANQUILIZERS AND NON-BARBITURATE SEDATIVE-HYPNOTICS
• Physiological signs of intoxication and overdose; they have typically
relatively little effect on autonomic nervous system functions; they
generally elevate the convulsion threshold; limited but significant
tolerance develops with the chronic heavy use; physical dependence can
also occur with high-dose use; psychological dependence is sometimes
reported; and significant but often incomplete cross-tolerance and cross-
dependence may mainly occur among them [7]. The various drugs may
differ to some extent typically in their potential for producing these
effects. The major exceptions to some of these generalizations about
sedative drugs are specific anticholinergic (acetylcholine blocking),
antihistaminic (histamine blocking) and bromide compounds, although
even these are similar to the other sedatives in many respects.
Furthermore, most of the volatile solvents and gases have somewhat
comparable sedative properties [8].

9. •
• Journal of Advances in Pharmacy Practices,
Barbiturates: Tranquilizers, S. Sreeremya,
2018.Vol 1(1):1-7.